[AMD Official Use Only - Internal Distribution Only]
Hi Christian,
Since amdgpu_debugfs_wait_dump() would need 'audodump.dumping.done==0' to actually stop and wait for user mode app to dump.
Since usermode app might open a file , do nothing and close it. I believe a poll() function would be a better indicator that the usermode app actually wants to do a dump.
Also, a reset might happen between open() and poll(). The worst case would be wait_dump() would wait until timeout and usermode poll would always fail.
Jiange
-----Original Message-----
From: Christian König <ckoenig.leichtzumerken@xxxxxxxxx>
Sent: Wednesday, May 13, 2020 4:20 PM
To: Zhao, Jiange <Jiange.Zhao@xxxxxxx>; amd-gfx@xxxxxxxxxxxxxxxxxxxxx
Cc: Deucher, Alexander <Alexander.Deucher@xxxxxxx>; Pelloux-prayer, Pierre-eric <Pierre-eric.Pelloux-prayer@xxxxxxx>; Zhao, Jiange <Jiange.Zhao@xxxxxxx>; Koenig, Christian <Christian.Koenig@xxxxxxx>; Liu, Monk <Monk.Liu@xxxxxxx>
Subject: Re: [PATCH] drm/amdgpu: Add autodump debugfs node for gpu reset v4
Am 09.05.20 um 11:45 schrieb jianzh@xxxxxxx:
> From: Jiange Zhao <Jiange.Zhao@xxxxxxx>
>
> When GPU got timeout, it would notify an interested part of an
> opportunity to dump info before actual GPU reset.
>
> A usermode app would open 'autodump' node under debugfs system and
> poll() for readable/writable. When a GPU reset is due, amdgpu would
> notify usermode app through wait_queue_head and give it 10 minutes to
> dump info.
>
> After usermode app has done its work, this 'autodump' node is closed.
> On node closure, amdgpu gets to know the dump is done through the
> completion that is triggered in release().
>
> There is no write or read callback because necessary info can be
> obtained through dmesg and umr. Messages back and forth between
> usermode app and amdgpu are unnecessary.
>
> v2: (1) changed 'registered' to 'app_listening'
> (2) add a mutex in open() to prevent race condition
>
> v3 (chk): grab the reset lock to avoid race in autodump_open,
> rename debugfs file to amdgpu_autodump,
> provide autodump_read as well,
> style and code cleanups
>
> v4: add 'bool app_listening' to differentiate situations, so that
> the node can be reopened; also, there is no need to wait for
> completion when no app is waiting for a dump.
>
> v5: change 'bool app_listening' to 'enum amdgpu_autodump_state'
> add 'app_state_mutex' for race conditions:
> (1)Only 1 user can open this file node
> (2)wait_dump() can only take effect after poll() executed.
> (3)eliminated the race condition between release() and
> wait_dump()
>
> v6: removed 'enum amdgpu_autodump_state' and 'app_state_mutex'
> removed state checking in amdgpu_debugfs_wait_dump
> Improve on top of version 3 so that the node can be reopened.
>
> Signed-off-by: Jiange Zhao <Jiange.Zhao@xxxxxxx>
> ---
> drivers/gpu/drm/amd/amdgpu/amdgpu.h | 2 +
> drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c | 78 ++++++++++++++++++++-
> drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.h | 6 ++
> drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 2 +
> 4 files changed, 87 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> index 2a806cb55b78..9e8eeddfe7ce 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> @@ -992,6 +992,8 @@ struct amdgpu_device {
> char product_number[16];
> char product_name[32];
> char serial[16];
> +
> + struct amdgpu_autodump autodump;
> };
>
> static inline struct amdgpu_device *amdgpu_ttm_adev(struct
> ttm_bo_device *bdev) diff --git
> a/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
> b/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
> index 1a4894fa3693..261b67ece7fb 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
> @@ -27,7 +27,7 @@
> #include <linux/pci.h>
> #include <linux/uaccess.h>
> #include <linux/pm_runtime.h>
> -
> +#include <linux/poll.h>
> #include <drm/drm_debugfs.h>
>
> #include "amdgpu.h"
> @@ -74,8 +74,82 @@ int amdgpu_debugfs_add_files(struct amdgpu_device *adev,
> return 0;
> }
>
> +int amdgpu_debugfs_wait_dump(struct amdgpu_device *adev) { #if
> +defined(CONFIG_DEBUG_FS)
> + unsigned long timeout = 600 * HZ;
> + int ret;
> +
> + wake_up_interruptible(&adev->autodump.gpu_hang);
> +
> + ret = wait_for_completion_interruptible_timeout(&adev->autodump.dumping, timeout);
> + complete_all(&adev->autodump.dumping);
> + if (ret == 0) {
> + pr_err("autodump: timeout, move on to gpu recovery\n");
> + return -ETIMEDOUT;
> + }
> +#endif
> + return 0;
> +}
> +
> #if defined(CONFIG_DEBUG_FS)
>
> +static int amdgpu_debugfs_autodump_open(struct inode *inode, struct
> +file *file) {
> + struct amdgpu_device *adev = inode->i_private;
> + int ret;
> +
> + file->private_data = adev;
> +
> + mutex_lock(&adev->lock_reset);
> + if (adev->autodump.dumping.done)
> + ret = 0;
> + else
> + ret = -EBUSY;
> + mutex_unlock(&adev->lock_reset);
> +
> + return ret;
> +}
> +
> +static int amdgpu_debugfs_autodump_release(struct inode *inode,
> +struct file *file) {
> + struct amdgpu_device *adev = file->private_data;
> +
> + complete_all(&adev->autodump.dumping);
> + return 0;
> +}
> +
> +static unsigned int amdgpu_debugfs_autodump_poll(struct file *file,
> +struct poll_table_struct *poll_table) {
> + struct amdgpu_device *adev = file->private_data;
> +
> + reinit_completion(&adev->autodump.dumping);
Why do you have the reinit_completion here and not in open callback?
Apart from that looks good to me.
Regards,
Christian.
> + poll_wait(file, &adev->autodump.gpu_hang, poll_table);
> +
> + if (adev->in_gpu_reset)
> + return POLLIN | POLLRDNORM | POLLWRNORM;
> +
> + return 0;
> +}
> +
> +static const struct file_operations autodump_debug_fops = {
> + .owner = THIS_MODULE,
> + .open = amdgpu_debugfs_autodump_open,
> + .poll = amdgpu_debugfs_autodump_poll,
> + .release = amdgpu_debugfs_autodump_release, };
> +
> +static void amdgpu_debugfs_autodump_init(struct amdgpu_device *adev)
> +{
> + init_completion(&adev->autodump.dumping);
> + complete_all(&adev->autodump.dumping);
> + init_waitqueue_head(&adev->autodump.gpu_hang);
> +
> + debugfs_create_file("amdgpu_autodump", 0600,
> + adev->ddev->primary->debugfs_root,
> + adev, &autodump_debug_fops);
> +}
> +
> /**
> * amdgpu_debugfs_process_reg_op - Handle MMIO register reads/writes
> *
> @@ -1434,6 +1508,8 @@ int amdgpu_debugfs_init(struct amdgpu_device
> *adev)
>
> amdgpu_ras_debugfs_create_all(adev);
>
> + amdgpu_debugfs_autodump_init(adev);
> +
> return amdgpu_debugfs_add_files(adev, amdgpu_debugfs_list,
> ARRAY_SIZE(amdgpu_debugfs_list));
> }
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.h
> b/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.h
> index de12d1101526..2803884d338d 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.h
> @@ -31,6 +31,11 @@ struct amdgpu_debugfs {
> unsigned num_files;
> };
>
> +struct amdgpu_autodump {
> + struct completion dumping;
> + struct wait_queue_head gpu_hang;
> +};
> +
> int amdgpu_debugfs_regs_init(struct amdgpu_device *adev);
> int amdgpu_debugfs_init(struct amdgpu_device *adev);
> void amdgpu_debugfs_fini(struct amdgpu_device *adev); @@ -40,3 +45,4
> @@ int amdgpu_debugfs_add_files(struct amdgpu_device *adev,
> int amdgpu_debugfs_fence_init(struct amdgpu_device *adev);
> int amdgpu_debugfs_firmware_init(struct amdgpu_device *adev);
> int amdgpu_debugfs_gem_init(struct amdgpu_device *adev);
> +int amdgpu_debugfs_wait_dump(struct amdgpu_device *adev);
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> index cc41e8f5ad14..545beebcf43e 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> @@ -3927,6 +3927,8 @@ static int amdgpu_device_pre_asic_reset(struct amdgpu_device *adev,
> int i, r = 0;
> bool need_full_reset = *need_full_reset_arg;
>
> + amdgpu_debugfs_wait_dump(adev);
> +
> /* block all schedulers and reset given job's ring */
> for (i = 0; i < AMDGPU_MAX_RINGS; ++i) {
> struct amdgpu_ring *ring = adev->rings[i];
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